1. Field of the Invention
This invention relates generally to a method and apparatus for cancelling vibrations in a physical system and more particularly to the method and apparatus for the adaptive cancelling of the vibrations in a mechanical structure caused by periodic forces acting on a rotating shaft.
2. Description of the Prior Art
Unwanted vibrations in mechanical structures are an ever occurring problem due to external and internal forces acting on them. Various types of passive shock absorber systems are well known for damping these undesired vibrations. More recently, however, active or adaptive shock absorber systems have been developed where counteractive sources are generated and applied to the system in response to sensed vibrational forces occurring as a function of time. One area of particular interest in vibration damping is the cancellation of periodic pulsating forces acting on a rotating shaft. Typically, in an adaptive vibration canceller utilized in connection with a rotating shaft, the shaft pulsation force is sensed by some type of pickoff device which then feeds a signal to a controller which drives a reaction device to impart a controlled force to the shaft which opposes the shaft pulsation force and thereby cancels the shaft vibration and thus the vibration in the surrounding environment
It is a primary object of the present invention, therefore, to provide an improvement in vibration cancelling systems.
It is another object of the invention to provide improvement in adaptive vibration cancelling systems
And yet another object of the invention is to provide an improvement in adaptive vibration cancelling systems for structures in the vicinity of or supporting rotating shafts.